1. Field of the Invention
The present invention relates to an impact power tool for performing a linear hammering operation on a workpiece, and more particularly to a technique for cushioning a reaction force received from the workpiece during hammering operation.
2. Description of the Related Art
Japanese non-examined laid-open Patent Publication No. 8-318342 discloses a technique for cushioning an impact force caused by rebound of a tool bit after its striking movement in a hammer drill. In the known hammer drill, a rubber ring is disposed between the axial end surface of a cylinder and an impact bolt. The rubber ring has a function of cushioning the impact force caused by rebound of the tool bit and positioning the hammer drill during a hammering operation. It is advantageous to make the rubber ring soft in order to absorb the rebound of the tool bit. On the contrary, it is advantageous to make the rubber ring hard in order to improve the positioning accuracy. Thus, while two different properties are required to the known rubber ring, it is difficult to provide the rubber ring with a hardness that satisfies the both functional requirements. In this point, further improvement is required.